The invention relates to surface preparation, cleaning, rinsing and drying of workpieces, such as semiconductor wafers, flat panel displays, rigid disk or optical media, thin film heads, or other workpieces formed from a substrate on which microelectronic circuits, data storage elements or layers, or micro-mechanical elements may be formed. These and similar articles are collectively referred to here as a xe2x80x9cwaferxe2x80x9d or xe2x80x9cworkpiecexe2x80x9d.
The semiconductor manufacturing industry is constantly seeking to improve the processes used to manufacture microelectronic circuits and components, such as the manufacture of integrated circuits from wafers. The objectives of many of these improved processes are decreasing the amount of time required to process a wafer to form the desired integrated circuits; increasing the yield of usable integrated circuits per wafer by, for example, decreasing contamination of the wafer during processing; reducing the number of steps required to create the desired integrated circuits; and reducing the costs of manufacture.
In the processing of wafers, it is often necessary to subject one or more sides of the wafer to a fluid in either liquid, vapor or gaseous form. Such fluids are used to, for example, etch the wafer surface, clean the wafer surface, dry the wafer surface, passivate the wafer surface, deposit films on the wafer surface, etc. Controlling how the processing fluids are applied to the wafer surfaces, is often important to the success of the processing operations.
Various machines and methods have been used for carrying out these manufacturing processes. However, existing machines have several disadvantages. These disadvantages include relatively large consumption of process chemicals and water. This consumption of process chemicals increases manufacturing costs, which ultimately increases the cost of the final product, such as e.g., computers, cell phones, and virtually all types of consumer, industrial, commercial and military electronic products. In addition, many process chemicals are toxic and require special handling, storage, and disposal methods. These can be costly and difficult, but are necessary for health, safety and environmental reasons. Consequently, reducing consumption of process chemicals has many advantages.
Reducing consumption of water is also beneficial. In many areas, water is becoming increasingly scarce. Due to population growth, there is greater competition for water. Disposing of waste water in environmentally friendly ways has also often become more difficult or costly. Accordingly, reducing water consumption in the manufacturing process is also important.
In many process manufacturing steps, the process chemicals used should be applied evenly onto the wafers, to avoid having too much or too little etching, film removal, etc. Existing machines often are not able to sufficiently uniformly apply process chemicals. This can result in lower yields. Moreover, many existing machines try to compensate for variations in applying process chemicals by using larger amounts of process chemicals. This inefficient use of process chemicals leads to the disadvantages described above. Accordingly, improved machines and methods which provide improved yield, consume less process chemicals and water, and offer better results in performing manufacturing operations, are needed.
Manufacturing semiconductor and similar products on a commercial scale requires a fab or manufacturing facility often costing hundreds of million dollars to build and equip. Operating and maintenance costs are also very high. Consequently, the output or yield of the fab is critical to successful operations. Faster processing can help increase the fab output. While conventional processing with liquids may produce the desired results, it can be time consuming. Accordingly, faster process methods and machines are very advantageous.
Machines and methods have now been invented which overcome the disadvantages described above. In one design, the machine includes a workpiece housing having a processing chamber. Processing fluids are distributed across the surface of the workpiece in the processing chamber, by centrifugal force.
In a preferred design, a process head holds a workpiece with the bottom of the workpiece uncovered or open. A base has a bowl for containing a liquid. A sonic energy source, such as a megasonic transducer, is associated with the bowl. The head moves to place the workpiece into contact with the liquid in the bowl. Sonic energy from the sonic energy source moves through the liquid to the workpiece, improving workpiece processing. The process head optionally rotates the workpiece while it is in contact with the liquid.
The use of sonic energy in these aspects expedites processing and provides more efficient processing. The use of sonic energy with reactors, such as described in International Patent Application No. WO 99/46064, (published Sep. 16, 1999 and incorporated herein by reference) which are currently in use is generally counter-intuitive, due to the often closed configuration; spinning rotors; and/or lack of a continuous liquid volume around the workpiece, in these reactors. It has now been discovered, however, that sonic energy can indeed be used in these types of reactors, providing improved processing.
Accordingly, it is an object of the invention to provide improved methods and apparatus for processing a workpiece. The invention resides as well in subcombinations of the steps and features described. The features described and illustrated in connection with one embodiment may or course be used in other embodiments as well.